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Blender 2.72: Cycles

Light influences the Volume on and off.

Volume Rendering

Volume sampling options can now be configured per world or material, and apply to both homogeneous and heterogeneous volumes. The sampling method can be "Multiple Importance", "Distance" or "Equiangular".

If you've got a pretty dense volume that's lit from far away then distance sampling is usually more efficient. If you've got a light inside or near the volume then equiangular sampling is better. If you have a combination of both, then the multiple importance sampling will be better.

Node setup created by Quick Smoke operator.

Other changes:

For branched path tracing, "Sample All Lights" options now apply to both surfaces and volumes.

Initial support for Volume Scatter Ray Visibility, to e.g. exclude lamps from having an influence on the volume. (cdd1d5a93c43)

GPU Rendering

Basic Volume Rendering is now officially available on GPUs. Note that advanced features are not available yet, check the documentation here for details. (8d0b3e990254)

Subsurface Scattering and Correlated Multi Jitter sampling can now be used on GPU as well, but it's still considered experimental: Experimental feature. We also recommend a GPU with at least 2GB of VRAM for this one. (fb3f32760d68)

Old and New Glossy Sampling.

Optimizations

Importance sampling for Glossy and Anisotropic BSDFs has been improved, which results in less noise per sample. The gives increased render time as well, but it's generally more than compensated by the reduction in noise.

CPUs with support for AVX2 (e.g. Intel Haswell) render a few percent faster. (866c7fb6e63d)

Shading

Anisotropic BSDFs now support three distributions: Beckmann, GGX and Ashikhmin-Shirley, the same as the Glossy BSDF. These distributions do not suffer from energy loss at grazing angles (edge darkening) as much as the previous distribution.

Glossy BSDFs now support the Ashikhmin-Shirley distribution.

Split the "No Caustics" option into two, so artists can only disable/enable refraction or reflection caustics. (8243c55f14ae)

All caustics on, only reflection, only refraction.

Anamorphic Bokeh

Anamorphic bokeh can now be simulated with the aperture ratio settings.

This affects the general look at the shot since even when the bokeh is not evident the depth of field shows a very particular vertical style. (146ed67d5591)